Such a pneumatic linear drive is known from DE 43 23 846 C1. This drive comprises a pneumatic piston and cylinder unit, a spring urging the piston rod in the direction of an end position, a lock member for engaging in a groove in a piston rod and a locking rod for displacing the lock member. Additionally, two separate chambers are provided which can be pressurized or vented to control the lock member and the piston. A disadvantage of this drive is that the lock member remains in contact with the piston rod producing damage thereof due to friction and ultimate malfunction.
DE 42 21 230 C1 discloses a similar construction of a drive in which the lock member is in surface contact with the piston rod thus having the same problem of frictional wear.